update arista-720dt port alias mapping (#6392)

What is the motivation for this PR?
According to SONiC port naming convention change (https://github.com/sonic-net/SONiC/blob/master/doc/sonic-port-name.md), update the port alias to etp1~etp52 for Arista-720DT.

How did you do it?
Update the port alias mapping in port_utils.py.

How did you verify/test it?
Verified on physical testbeds.

Author: lizhijianrd

ansible/module_utils/port_utils.py

@@ -229,8 +229,8 @@ def get_port_alias_to_name_map(hwsku, asic_name=None):
             for i in range(0, 256, 8):
                 port_alias_to_name_map["Ethernet%d" % i] = "Ethernet%d" % i
         elif hwsku == "Arista-720DT-48S":
-            for i in range (1,53):
-                port_alias_to_name_map["Ethernet%d" % i] = "Ethernet%d" % (i - 1)
+            for i in range(1, 53):
+                port_alias_to_name_map["etp%d" % i] = "Ethernet%d" % (i - 1)
         else:
             for i in range(0, 128, 4):
                 port_alias_to_name_map["Ethernet%d" % i] = "Ethernet%d" % i